package com.dsh.guns.modular.system.util.three;

public class Base64Coder {
	public final static char[] base64_alphabet = new char[] { 'A', 'B', 'C',
			'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
			'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c',
			'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p',
			'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2',
			'3', '4', '5', '6', '7', '8', '9', '+', '/', '=' };

	public static String encode(byte[] data) {
		int length = data.length;
		byte[] char_array_3 = new byte[] { 0, 0, 0 };
		byte[] char_array_4 = new byte[] { '=', '=', '=', '=' };
		String retContent = "";
		int i = 0;
		int j = 0;
		int reversePos = 0;
		while (length > 0) {
			length--;
			char_array_3[i++] = data[reversePos++];
			if (i == 3) {
				char_array_4[0] = (byte) ((char_array_3[0] & 0xfc) >> 2); // convert
																			// the
																			// char
				char_array_4[1] = (byte) (((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4));
				char_array_4[2] = (byte) (((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6));
				char_array_4[3] = (byte) (char_array_3[2] & 0x3f);
				for (i = 0; (i < 4); i++) {
					retContent += base64_alphabet[char_array_4[i]];
				}
				i = 0;
			}
		}

		// handling the last input content
		if (i > 0) {
			for (j = i; j < 3; j++) {
				char_array_3[j] = 0; // padding of zero
			}

			char_array_4[0] = (byte) ((char_array_3[0] & 0xfc) >> 2); // right
																		// shift
			char_array_4[1] = (byte) (((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4));
			char_array_4[2] = (byte) (((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6));
			char_array_4[3] = (byte) (char_array_3[2] & 0x3f);

			for (j = 0; (j < i + 1); j++) {
				retContent += base64_alphabet[char_array_4[j]];
			}

			while ((i++ < 3))
				// padding of '=' of output string
			{
				retContent += '=';
			}

		}
		return retContent;
	}

	public static String decode(String enContent) {
		byte[] data = enContent.getBytes();
		int i = 0, j = 0, enCode = 0;
		int mLength = data.length;
		byte[] char_array_4 = new byte[4];
		byte[] char_array_3 = new byte[3];
		String retContent = "";

		// filter out the padding '=' chars
		while (mLength > 0 && (((char) data[enCode]) != '=')
				&& isBase64((char) data[enCode])) {
			mLength--;
			char_array_4[i++] = data[enCode++];
			if (i == 4) {
				for (i = 0; i < 4; i++) {
					char_array_4[i] = findChar((char) char_array_4[i]);
				}

				char_array_3[0] = (byte) ((char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4));
				char_array_3[1] = (byte) (((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2));
				char_array_3[2] = (byte) (((char_array_4[2] & 0x3) << 6) + char_array_4[3]);

				for (i = 0; (i < 3); i++) {
					retContent += (char) char_array_3[i];
				}
				i = 0;
			}
		}

		// last content handling
		if (i > 0) {
			for (j = i; j < 4; j++) {
				char_array_4[j] = 0;
			}

			for (j = 0; j < 4; j++) {
				char_array_4[j] = findChar((char) char_array_4[j]);
			}

			char_array_3[0] = (byte) ((char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4));
			char_array_3[1] = (byte) (((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2));
			char_array_3[2] = (byte) (((char_array_4[2] & 0x3) << 6) + char_array_4[3]);

			for (j = 0; (j < i - 1); j++) {
				retContent += (char) char_array_3[j];
			}
		}

		return retContent;
	}

	public static boolean isBase64(char c) {
		boolean base64 = false;
		for (int i = 0; i < 64; i++) {
			if (c == base64_alphabet[i]) {
				base64 = true;
				break;
			}
		}
		return base64;
	}

	public static byte findChar(char x) {
		byte index = 64; // 65th char '='
		for (int i = 0; i < 64; i++) {
			if (x == base64_alphabet[i]) {
				index = (byte) i;
				break;
			}
		}
		return index;
	}

}